Grinding machine



NOV. 2, 1937. 3- CASEY 2,097,944

GRINDING MACHINE Filed Feb. 1, 1937 y l Vl IIIIIIHII-v IIN/Hl INVENTOR,LEDGEWORTH G CASEY MMMQMW ATTORNEY.

Patented Nov. 2, 1937 PATENT oFFlcE GRINDING MACHINE Ledgeworth G.Casey, Cincinnati, Ohio, assigner to The Cincinnati Electrical ToolCompany,' Cincinnati, Ohio, a corporation of Ohio Application Februaryl,1937, Serial No. 123,328

8 Claims.

My invention pertains to grinding machines and more particularly to thedriving mechanism for the grinding element or grinding wheel of suchmachines.

'I-Ieretofore, it has been Vdifficult to provide a smooth drive to agrinding wheel which was subjected to intermittent cutting operations ona work piece such as is encountered in hand grinding and snaggingoperations. In such operations f, there is a tendency for the grindingwheel to momentarily drive the driving motor at the instant the wheel isremoved from the work piece because of its usually greater mass andmomentum which causes it to be less susceptible to 3 changes in speedthan the armature of its driv- .Y nonconformity of motion objectionablein grinding machines wherein the transmission connecting the drivingmotor to the grinding wheel has slack or backlash, such for example asis found in the usual reduction gearing between the motor and thegrinding wheel in portable electric hand grinding tools, because of thechatter and vibration set up which tends to destroy the transmission andthe accuracy of the grinding operations.

An object of my invention is to provide in a grinding machine, betweenthe driving motor and the grinding wheel, a transmission mechanismwherein the motor may drive the grinding wheel but the grinding wheelmay not drive the motor.

Another object is to provide in a grinding machine, a motor and agrinding Wheel and a transmission mechanism incorporating anover-running clutch connecting said motor to said grinding wheel wherebythe momentum of the grinding wheel can not cause said wheel to driveVthe motor.

And a further object is to provide in a hand grinder, a motor andgrinding wheel and a gear reduction transmission mechanism incorporatingan over-running clutch connecting said motor to said grinding wheel.

Other objects of this invention will be understood from the followingdetailed description of the drawing, in which:

Figure I is a plan View partly in section on line I-I of Figure IIshowing an exemplary embodiment of my invention in a portable electrichand grinder.

Figure II is a transverse section through the transmission mechanism online II-II of Figure I.

As an exemplary embodiment I show my invention applied to a portableelectric hand grinder comprising the usual electric motor housing lI andswitch handle 2 to which is attached the electric supply cord 3.Connected to the motor housing I by suitable screws 4 is the bear- 5 ingplate 5 and the grinding wheel spindle housing 5. The grinding wheelspindle 1 is journaled in bearing 8, in housing 5 and in bearing I0 inthe plate 5. A grinding wheel I I is appropriately mounted on the wheelspindle 'I by the usual l0 mounting means I2.

The armature shaft I3 of the armature I4 of the motor I5 in the housingI is journaled in the bearing l5 in the plate 5 and has a pinion I'Ifixed thereon which engages the ring gear I8. Journaled on the bearingportion I9 of the spindle l isthe cup member which has a hub portion ZIwhich is journaled in the bearing 22 mounted in the housing 6, therebyproviding free rotation of cup on the spindle 'I while at the 20 sametime providing an adequate intermediate support for said spindle. Thering gear I8 is xed on the `outside portion of the cup 25 and held inpositive driving relation by means of the key 23.

Fixed in driving relation on the spindle l is the star wheel 24 by meansof key 24a which has the rollers- 25 associated therewith in the usualmanner for an over-running clutch. A suitable disc 25 also xed on thespindle 'I ad- 30 jacent the bearing I serves to maintain the rollers 25in proper axial relation to the star wheel 24 and cup 25.

The over-running clutch comprising the cup 2li, the star wheel 24 andassociated rollers 25 are 35 so arranged that driving power may bedelivered from armature I4 through the pinion I'I and ring gear I8 todrive the spindle l, but the spindle can not drive the ring gear I8. Theresult of providing such an arrangement. is to cause the ring gear I8 toat all times be driven by the pinion and to prevent the spindle 1 fromcausing the gear I8 to drive or tend to accelerate the speed of rotationof the motor pinion and armature I4 thus preventing any backlashmovement be- 45 tween the pinion I'I and the gear I8 and its inherentchatter and vibration.

Having described my invention, what I claim as new and desire to secureby United States Letters Patent is:

l. In a grinding machine, a frame, a grinding wheel spindle rotatablymounted in said frame, a grinding wheel mounted on said spindle, a motorincorporated in said frame having an armature mounted on an armatureshaft rotatably mounted 55 in said frame, a driving pinion on saidarmature shaft, an over-running clutch mounted on said wheel spindle,and a gear associated with said over-running clutch and engaged by saidpinion whereby said motor may drive said grinding Wheel and saidgrinding wheel may not drive said motor.

2. In a grinding machine, a frame, a grinding Wheel spindle journaled insaid frame, a grinding Wheel mounted on said spindle, a motorincorporated in said frame having an armature mounted on an armatureshaft rotatably mounted in said frame, a driving pinion Xed on saidarmature shaft, an over-running clutch mounted on said Spindlecomprising a star W'heel x'ed to said spindle, a cup journaled on saidspindle, and associated rollers, and a ring gear fixed to said cup andadapted to be driven by said pinion whereby said grinding wheel may bedriven by said motor and said grinding Wheel may not drive said motor.

3. In a grinding machine, a frame, a grinding wheel spindle journaled insaid frame, a grinding Wheel mounted on said spindle, a motorincorporated in said frame having an armature mounted on an armatureshaft rotatably mounted in said frame, a driving pinion fixed on saidarmature shaft, an over-running clutch associated With said spindlecomprising a star wheel Xed to said spindle, a cup rotatably mounted onsaid spindle and in said frame, and associate rollers, and a gear xed tosaid cup and adapted to be driven by said pinion 'whereby said motor maydrive said grinding wheel and said grinding wheel may not drive saidmotor.

4. In a portable electric hand grinder having wheel spindle, motor, andswitch handle portions, a grinding Wheel spindle rotatably mounted insaid wheel spindle portion, a grinding wheel mounted on said spindle, anarmature mounted on an armature shaft rotatably journaled in said motorportion, a pinion Xed on said armature shaft, an over-running clutchassociated with said wheel spindle, comprising a star wheel Xed on saidspindle, a cup journaled on said spindle, and associated rollers, and agear xed on said cup adapted to be driven by said pinion whereby saidmotor may drive said grinding Wheel and said grinding wheel may notdrive said motor.

5. In a portable electric hand grinder, a frame, a wheel spindlerotatably mounted in said frame, a grinding wheel mounted on said wheelspindle, an electric motor incorporated in said frame, an over-runningclutch mounted on said wheel spindle, and means inter-connecting saidmotor with said clutch whereby said Wheel spindle may be rotated by saidmotor and said motor may not be rotated by said Wheel spindle.

6. In a grinder, a frame, a wheel spindle rotatably mounted in saidframe, a grinding wheel mounted on said wheel spindle, an electric motorincorporated in said frame, an over-running clutch mounted on said Wheelspindle, and means inter-connecting said motor with said clutch wherebysaid wheel spindle may be rotated by said motor and said motor may notbe rotated by said wheel spindle.

7. In a grinder, a frame, a wheel spindle rotatably mounted in saidframe, a grinding wheel mounted in said frame, a grinding wheel mountedon said wheel spindle, an electric motor incorporated in said frame, anover-running clutch mounted on said wheel spindle, and lgear-reductionmeans inter-connecting said motor with said clutch whereby said Wheelspindle may be rotated by said motor and said motor may not be rotatedby said wheel spindle.

8. In a grinder, a frame, a wheel spindle rotatably mounted in saidframe, a grinding wheel mounted on said Wheel spindle, an electric motorincorporated in said frame, inter-connecting means including anover-running clutch between said motor and said wheel spindle wherebysaid wheel spindle may be rotated by said motor and said motor may notbe rotated by said Wheel spindle.

LEDGEWORTI-I G. CASEY.

